Is he doing out of "cruelty" or because you unfortunately didn't manage to get the grades in the year?
If you think it is the former, then I would go to speak to someone higher in the school because that is just unfair if you are an "A* student".
If it is because you did not get the grades in the year, then he can't give privileges to you just because you want to go to Oxford, but then again, I have no idea what your story is or who you are, so I am not going to judge.
I would still apply, because you never know that you won't do amazingly well in the PAT, get an offer (though it may be relatively high), and blow away an interviewer.
I wish you the very best of luck!